Gas dispersing apparatus

ABSTRACT

An apparatus for dispersing gas in liquid mediums comprising a rigid adapter, a rigid tubular inner member secured to the adapter cooperating with a passage in said adapter to form a continuous conduit for gas, a terminal member for said rigid tubular inner member, a flexible, collapsible porous sleeve, having one permanently closed end and a peripheral dimension approximately equal to the peripheral dimension of a cross section of said tubular member, enclosing said tubular member and said terminal member and secured to the adapter to form an air chamber between the tubular member and the sleeve, said terminal member having means for passage of gas between the interior of the tubular member and the closed end of said sleeve and separate communication means connecting the closed end of said sleeve and the longitudinally extending space between the sleeve and said tubular member.

United States Patent [72] Inventor Leonard M. Nechine Highland Park, Ill. [21] Appl. No. 14,255 [22] Filed Feb. 24, 1970 [45] Patented Sept. 7, 1971 [73] Assignee FMC Corporation 54] GAS DISPERSING APPARATUS 3 Claims, 4 Drawing Figs.

[52] US. Cl 239/145, 239/590.3,261/l22 [51] Int. Cl B0ld 47/02 [50] Field of Search 239/145, 590.3, 537, 542; 261/122, 64

[56] References Cited UNITED STATES PATENTS 3,279,773 10/1966 Schwartz 239/145 X 3,315,895 4/1967 Klingbeil et al 239/145 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Michael Y. Mar Attorney-Dressler, Goldsmith, Clement & Gordon ABSTRACT: An apparatus for dispersing gas in liquid mediums comprising a rigid adapter, a rigid tubular inner member secured to the adapter cooperating with a passage in said adapter to form a continuous conduit for gas, a terminal member for said rigid tubular inner member, a flexible, collapsible porous sleeve, having one permanently closed end and a peripheral dimension approximately equal to the peripheral dimension of a cross section of said tubular member, enclosing said tubular member and said terminal member and secured to the adapter to form an air chamber between the tubular member and the sleeve, said terminal member having means for passage of gas between the interior of the tubular member and the closed end of said sleeve and separate communication means connecting the closed end of said sleeve and the lon gitudinally extending space between the sleeve and said tubular member.

PATENTED SEP 7 19?] IHI GAS DTSPERSING APPARATUS This invention relates to apparatus for aeration of liquid or for the dispersion of gases or vapors therein. More particularly, it relates to gas-diffusing elements having an outer sheath member of collapsible foraminated fabric and an inner solid tubular member extending substantially the entire length of said sheath to introduce air or gas under pressure into said sheath for discharge through the interstices thereof in fine bubble form.

Diffusers of the type with which the present invention is concerned are employed in the activated sludge precess of treating sewage or flotation processes, treatment of industrial wastes, various fermentation processes and other chemical processes where gas-liquid contact is essential.

Diffusers for the instant purposes heretofore in use have been formed by wrapping cord about a hollow foraminated core or by attaching a cloth sleeve member to a fixture having an air passage therethrough adapted to communicate with the interior of the sleeve. Such air diffusers may have a skeletal frame member or a solid core member within the sleeve coextensive in length therewith to maintain the sleeve in an axially extended position.

To hold the sleeve members in proper alignment at all times with the inner structures requires a careful balancing of tautness. This balancing of tautness is particularly critical in the type of diffuser shown in Lamb U.S. Pat. No. 3,206,178. in this apparatus, air only enters directly into the upper section of the air chamber and the fabric must inflate sufficiently to allow airflowing in the upper section to pass between the ribs and fabric and thus to pass from one section of the air chamber to another. While the fabric must be sufficiently extensible for passing gas from one section to another, the fabric must not be of a size to permit the fabric to fold upon itself when it is collapsed to cause the fabric to strike against the inner member or else there will not be sufficient force to achieve the desired action of breaking away substantially all of the solid foreign matter accumulated thereon.

Now it has been discovered that effective cleaning action may be accomplished while having greater freedom of movement for the fabric and a uniform discharge of gas over the entire circumference of the foraminous outer sheath if a diffuser tube comprises a rigid adapter fitting, a rigid tubular member secured at one end to said adapter fitting, said tubular member having a substantially uniform cross-sectional area between its ends reduced from that of said fitting, an inlet for gaseous medium extending axially through said adapter fitting and communicating with the interior of said tubular member, a terminal member for the cantilever end of said tubular member, said terminal member having an exterior configuration and size approximating that of said adapter fitting and adapted for sliding fit engagement with the exterior of said tubular member, the engagement being at circumferentially spaced zones of contact that provide axially extending open areas between said terminal member and said tubular member, a flexible, collapsible, porous sleeve member having one permanently closed end, means providing a substantially airtight connection between the other end of said sleeve and said adapter fitting whereby the sleeve member which is of substantially uniform cross section throughout its length and of cross-sectional area and configuration approximately equal to that of said adapter fitting completely encloses said tubular member and forms an air chamber between said tubular member and said sleeve member, said terminal member in its cross-sectional area coextensive with the cross-sectional area of the end of said tubular member providing means for passage of gas between the interior of said tubular member and the interior of the permanently closed end of said sleeve member, said terminal member further providing communication means through the areas intermediate said spaced zones of contact with said tubular member between the interior of the permanently closed end of said sleeve member and the air chamber formed between said tubular member and said sleeve member for passage of gas.

in such a diffuser tube, the sleeve member has a length substantially greater than the width or height thereof. The sleeve member is attached to a rigid adapter fitting which is preferably cylindrical and has a nipple that is externally threaded or is provided with other attachment means so that the nipple may be easily connected to an air supply pipe. Air or gas passes through the inlet passage into the interior of the tubular member from which it passes through the outer end of said tubular member into the closed end of said porous sleeve member which is spaced from the end of the tubular member a distance insuring that gasflow out of the tubular member and back to the air chamber surrounding the tubular member is not throttled.

The gas due to unrestricted communication between air passages and air chambers is under a uniform pressure over the entire periphery of the air chamber and the air passes through the porous sleeve member to the surrounding medium with substantially uniform distribution.

Such a porous sleeve member may be made of flexible, porous, woven fabric suitably of a plastic material. Thus, it may be made from a synthetic linear polyamide such as nylon, from a copolymer of vinyl chloride and vinylidene chloride of the type known commercially as Saran or other synthetic plastic material, from canvas or other suitable textile material or from porous metal fabric or other suitable fabric capable of withstanding the action of sewage and the pressure of the liquid in which it is immersed and yet to be flexible enough to be collapsed quickly when the air or gas supply is shut off.

The interstices of the fabric through which the air or gasflows may be varied as desired, but preferably are small enough to cause the air or gas to pass through in fine bubble form to provide more efficient aeration or gasification.

The inner tubular member may be made of wood, metal, plastic or any other suitable solid, rigid material. Typical suitable plastics are urea-formaldehyde, polyvinyl chloride, polystyrene, modified styrenes or other thermosetting types of resin.

The inner tubular member is preferably formed as a trifurcate shell. The shell has three spaced portions. The maximum diameter of a spaced portion is only slightly reduced from that of the adapter. In between these three spaced portions, the diameter of the shell is further reduced along three circumferentially spaced longitudinally extending lines with the surface between said lines being of a convex configuration so that the exterior of the shell has a shallow depression formed between the spaced portions constituting equally spaced, equal length lobes. When the tubular member having such an undulating exterior surface is enclosed in a porous sleeve member, the shallow depressions, preferably having a smooth concave surface for their bottoms, become the enlarged areas of an air chamber formed between the sleeve member and the exterior of the tubular member.

The surfaces of the shallow depressions provide a surface against which the portion of the sleeve member coextensive therewith strikes, when the sleeve is rapidly deflated, to dislodge solid foreign matter accumulated on its surface and in its pores. To have effective striking action, the difference between the surface area of the sleeve member and said tubular member must be such that the entire portion of the sleeve member strikes against the tubular member, particularly the concave surfaces thereof.

The aeration apparatus includes a quick acting valve that is located in the air supply line so that the diffuser tube is vented to the atmosphere simultaneously with the closing of the air supply line. The venting of the diffuser tube to the atmosphere causes the sleeve member to collapse quickly upon shut off of the air pressure. The sleeve due to proportioning relative to the inner tubular member enclosed therein, makes striking contact over substantially its entire length with the surfaces of the air chamber. When the quick acting valve is closed, the tube is reinflated. This sudden reinflation serves to break away solid foreign matter that is not broken away when the outer member strikes the inner member of the tube. Solid matter that is not broken away is sufficiently loosened in the pores of the porous sleeve member so that it will be blown out by the pressure of the air when the tube is inflated. Thus, the diffuser tubes are kept quite clean by periodic opening and closing of the air valve to deflate and reinflate the sleeves with the result that the maintenance expense of the present system is relatively low.

The diffuser tube of the present invention may be used individually or a plurality of such tubes may be ganged together. It is preferred to connect a plurality of such tubes to an air supply pipe with the tubes arranged in parallel relationship. The tubes are made relatively long relative to the width and height thereof.

A structure by means of which the above-mentioned and other advantages of the invention may be attained will be described in the following specification taken in conjunction with the accompanying drawings showing a preferred illustrative embodiment of the invention, in which:

FIG. 1 is a partial elevation in sectional view taken on line 1 1 of FIG. 3;

FIG. 2 is a sectional view along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view along the line 3-3 of FIG. 1; and

FIG. 4 is a view along the line 44 of FIG. 3.

Referring to the drawings, the diffuser tube comprises a rigid nonporous tubular inner member 11 and a flexible, collapsible porous outer sleeve member 12 which has a length slightly longer than said inner member 11 so that when the sleeve is flattened and its edges secured to provide a permanently closed end, the sleeve will still have a uniform diameter over' the length where the sleeve and tubular member are coextensive.

Sleeve 12 may be fabricated in the form of a continuous seamless unit and then cut into sections of desirable length to form individual sleeves. Sleeve 12 may also be formed from a flat sheet of the desired material and secured along the longitudinal edges by sewing to produce a tubular sleeve inflata ble to a circular configuration.

It is preferred to make the area at the closed end of the sleeve substantially airtight so that the air passing from the sleeve into the sewage must pass through the interstices of the fabric of which the sleeve is made.

The open end 14 of sleeve 12 is secured to an adapter fitting 15 which may be cast or molded of any suitable material such as the metals, iron or aluminum, etc, or moldable synthetic plastics such as acrylonitrile butadiene styrene resin, for example, material sold under the trade name Cycolac." The adapter fitting may have any desired shape but preferably includes a cylindrical section 16 which has a circumference 17 substantially equal to the circumference of the sleeve when the sleeve 12 is in its inflated condition. The open end of sleeve 12 may be secured to the adapter fitting 15 by any means capable of providing a substantially airtight connection and structurally secured therebetween. Sleeve 12 is secured to adapter 15 by clamp 18 which includes screw means 19 adapted to tighten or loosen the clamp and to hold it in position, providing an airtight connection between adapter 15 and sleeve 12.

Adapter fitting 15 has a projection 20, preferably integral therewith, that extends from the face thereof for connection to an air supply line (not shown). The outer section 21 of the projection is threaded as indicated at 22 so that it can be secured into engagement with an air supply line.

An axial bore 24 extends through adapter fitting 15 and projection 20 to provide an air, inlet for the flow of air from the supply line to and through the tubular member 11. The air inlet also provides a passageway through which air from the diffuser tube flows in the opposite direction to the atmosphere when the diffuser is deflated.

The tubular member 11 is formed between its ends with a trifurcate shell 25, preferably symmetrical about the longitudinal axis so as to form a central air passage 26 and to sectionalize the air chamber. The outer edge of each lobe furthest removed from the longitudinal axis is separated from that axis a distance just slightly shorter than the radius of the porous sleeve 12. The perimeter'of said tubular member 11 between said lobes has outer surfaces 27, 28 and 29 forming the bottom of each section of the air chamber. Surfaces 27, 28 and 29 are slightly curved. The portion of the porous sleeve 12 that is coextensive with the bottom of the air chamber strikes against the bottom surface of said air chamber throughout substantially the entire length of the outer member as illustrated in FIG. 2 to dislodge solid foreign matter as hereinbefore described.

FIGS. 3 and 4 show the position of the porous sleeve 12' when gas is flowing and the sleeve is inflated. Sleeve 12 contacts the ends of each leg of the trifurcated shell 25 and is spaced from the surfaces 27, 28 and 29 so as to form air chamber segments 30, 31 and 32.

A central air passage 26 extends through tubular member 1 l to direct air to the closed end of the porous sleeve member. The central air passage 26 has a trifurcate cross-sectional configuration, preferably symmetrical about the longitudinal axis. When the tubular member 1 l is formed with a trifurcate crosssectional configuration, each of the three lobes has a length, i.e., an anticlinal axis measured from the longitudinal axis of said tubular member, just slightly shorter that the radius of the porous sleeve 12.

The surface of said tubular member 11 at points intermediate the anticlinal axis terminals have a synchinal axis measured from the longitudinal axis of said tubular member 1 1 productive of a cross-sectional area with depressions giving rise to a cloverleaf like perimeter. The space in the depression areas between the surface of the tubular member 11 and the sleeve provides an air chamber formed with three enlarged areas 30, 31 and 32. The are defining the bottom surface of each section of the air chamber is shallower than the arc of the sleeve member 12. Thus, the surface area of the concave surface of a section of the air chamber is slightly less than the surface area of the portion of the sleeve coextensive therewith. Each area is provided with a shallow curved bottom to provide a concave surface against which the sleeve strikes when the diffuser is rapidly deflated.

Tubular member 11 is provided with a terminal member 35. Terminal member 35 is formed as a ring member 36 having a shoulder 37 of a shape to form a sliding fit with the interior of the trifurcate tubular member 11. Airflowing through the tubular member 11 passes through a port 38 in ring member 36, is reversed in its direction of flow by the closed end of sleeve 12 and passes through passage means 39 into the air chamber sections 30, 31 and 32.

Iclaim:

1. Gas diffusing apparatus comprising a rigid adapter fitting, a rigid tubular member secured at one end to said adapter fitting, said tubular member having a substantially uniform cross-sectional area between its ends reduced from that of said fitting, an inlet for gaseous medium extending axially through said adapter fitting and communicating with the interior of said tubular member, a terminal member for the cantilever end of said tubular member, said terminal member having an exterior configuration and size approximating that of said adapter fitting and being adapted for sliding fit engagement with said tubular member at circumferentially spaced zones of contact whereby axially extending open areas are provided between said terminal member and said tubular member, a flexible collapsible, porous sleeve member having one permanently closed end, means providing a substantially airtight connection between the other end of said sleeve and said adapter fitting whereby the sleeve member which is of substantially uniform cross section throughout its length and of cross-sectional area and configuration approximately equal to that of said adapter fitting completely encloses said tubular member and forms an air chamber between said tubular member and said sleeve member, said terminal member in its cross-sectional area coextensive with the cross-sectional area of the end of said tubular member providing means for passage of gas between the interior of said tubular member and the interior of the permanently closed end of said sleeve member, said terminal member further providing communication means through the area intermediate said spaced zones of contact with said tubular member between the interior of the permanently closed end of said sleeve member and the air chamber formed between said tubular member and said sleeve member for passage of gas.

2. Apparatus according to claim 1 wherein the tubular 

2. Apparatus according to claim 1 wherein the tubular member between its ends is reduced along three circumferentially spaced longitudinally extending lines, the portions of reduced cross-sectional area being shaped to provide a plurality of concave surfaces.
 3. Apparatus according to claim 1 wherein the difference between the surface area of said tubular member and the surface area of the sleeve member coextensive therewith being such that the entire portion of the sleeve member strikes against the concave surface of said tubular member. 